Freezing Tolerance of Transgenic Tobacco with Increased Content of Unsaturated Fatty Acid by Expressiong the CvFad3 Gene

Two fatty acid desaturases were independently expressed in tobacco plants and freezing torelance of the transgenic plants was investigated: the two disaturases were CvFAD2, which desaturases microsomal C18:1(oleic acid) to C18:2(lonoleic acid), and CvFAD3, which desaturates microsomal C18:2 to C18:3 (linolenic acid). Fatty acud conposition analysis showed that the C18:2 contents in the plants transformed with pBE2113/CvFad2 did not increase compared with that of the wild-type plant. However, an increase in the C18:3 content by 2.4% was observed in the line of No.19 although the increase was not statistically significant. In the plant transformed with pBE2113/CvFad3, the C18:3 content incerased by 6.4% compared with that of the wild-type plant. Measurement of the electolyte leakage of the wild-type plant at all temperatures investigated (from -1 to -4℃). Contrary to the case of the CvFad2, the freezing tolerance of the CvFad3 plant tended to be slightly lower than that of the wild-type at all temperatures tested despite the unsaturation levels of the plant were higher than those of the CvFad2 plants